Sam Burgess's early return to rugby league has left England short of a potentially international-class back-rower, says Bath coach Mike Ford.
Burgess, 26, left the Premiership side on Thursday to return to Australian NRL club South Sydney Rabbitohs.
He made the decision after being part of England's poor World Cup campaign.
"The way we play rugby at Bath he would have fitted in brilliantly and taken our game, and rugby union I feel, to a new dimension," said Ford.
Burgess switched codes and moved to Bath last year, before the recent Rugby Union World Cup.
But he has returned to Rabbitohs, citing "family reasons", with two years of his three-year contract remaining.
The Yorkshireman had been playing at blind-side flanker for Bath, but was picked at centre for England against Wales in the World Cup.
His selection led to much debate, with many observers suggesting the newcomer should have been allowed time to develop in just one position.
Ford is adamant Burgess could cope with playing in both positions, despite personally seeing his future at number six.
"No-one can change my mind that Sam Burgess is a back-row player - that's who he is," the 49-year-old former rugby league player told BBC Radio 5 live.
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"We wanted him on the field as a ball carrier and a tackler, that's what he did and it worked for us the way we played.
"Going from six to 12 for how England wanted to play, it's the same job. But with Bath he touched the ball more, made more tackles, had more involvements.
"I said to him he could play 12 with England then easily come back to us and play six. I stand by that.
"It's disappointing as I feel he has potentially left too early and we're short of a very good back-row player, and England are short of a potentially good back-row player internationally."
Burgess was given time off by Bath after England's World Cup campaign, returning earlier this week and had been poised to start on the bench in Saturday's Premiership win at London Irish.
"In that 10 days he's gone away and discussed his future to his fiancée Phoebe, he's come back in and he's still not right," said Ford after the 45-14 victory.
"On Monday, we spoke to him and there was still light at the end of the tunnel that he was going to play for Bath.
"He trained Monday, he trained Tuesday, we picked him in the team today to start on the bench, but from late on Wednesday South Sydney rang up and started negotiating with Bath.
"We had one more chance with Sam where we sat down with him and he kept saying it was for family reasons and he wanted to go back home."